GE IMP2B 数据表

Test Solution Components 

BIT is an initialization test, running at any  
power-up or re-initialization cycle. This
means it can achieve very high test
confidence levels (or test ‘coverage’) by
assuming complete ownership of all board
resources, utilizing these in the manner best
suited to the purpose of testing, right down
to the intimate register level. Very high coverage
levels with a detailed error resolution can
only be achieved in this way. Though the BIT
coverage level varies on individual hardware
products, this level is generally 95% or better.
BIT executes before any operating system
or even boot firmware, passing control to
these upon completion.

BCS is a continuous test and operates while
the application and the OS are running.
This provides early warning of problems
tothe application. In a typical COTS environment,
continuous tests are generally more limited
in scope than initialization tests. This is
because they must be non-intrusive, i.e.
their use of resources has to take into
account that neither the OS, nor any layered
software packages, nor the application,
can be disturbed. (Although COTS operating
systems have known, stable, published
interfaces, their internal use of hardware
resources is often complex, largely unpublished,
and assumed to be exclusive. Such usage also
varies with each OS type and even each
release.) While non-intrusion makes BCS
subject to limitations on test confidence and
diagnostic resolution, its major device usage
is via OS mechanisms, and thus it does not
conflict with the OS use of resources.

BCS is customized by GE Intelligent Platform
to each particular OS type and runs asan
OS thread. It thus avoids the danger created
if the application attempts to call a traditional
initialization test firmware (written in ignorance 
of the particular OS being used and usually
assuming exclusive control), to provide a
‘continuous’ test. This will likely compromise
the total machine state before returning to
the OS and application level. BCS allows
continuous testing even with a COTS
operating system.

Figure 1 represents the software modules
that GE Intelligent Platform supplies, showing
how BIT and BCS fit into the overall picture.
GE Intelligent Platform provides all modules
below the dotted black line. At the lowest
level, BIT and the boot firmware (SilverChip,
PPCBoot or a VxWorks BootROM) live
directly above the hardware.

These are self-contained modules that
have no interaction with higher levels,
except to pass control and data to them
upon completion. At the next level, the BSP
forms the hardware-dependent portion of
the operating system, still directly touch-
ing hardware but actually as part of the
context of the OS kernel itself. Additional
drivers extend this basic hardware layer to
support peripheral devices, and BCS has
similar characteristics to these, dealing
directly with hardware devices but as a
dedicated OS thread.

BIT and BCS form the key elements of a
total system test philosophy that allows
maximum test confidence for deployed
systems implemented with COTS hardware 
and software. BIT provides very high coverage 
initialization tests, BCS provides non-
intrusive background testing that is
co-operative with COTS operating systems.
Straightforward methods for the addition
of customized tests to cover customer-
proprietary items and special system
configurations complete the picture.

Bit and BCS:

Features and Operations

BIT anuc BIT executes in functional layers
(see Figure on front page), each providing
the confidence that further testing on the
next layer is valid. The Minimum Processing
Environment (MPE) executes first. This
sets up the basic board configuration and
performs tests to provide confidence in
the fundamental processing capability,
including Flash checksums and tests of
the (minimum) areas of memory required
for further BIT progress. Testing then
proceeds to local devices, PMC daughter
cards, and finally to other GE Intelligent
Platform elements within the total system.

Deployed Test Solutions

Default power-up configurations for 
GE Intelligent Platform boards are tailored
to give the optimum system confidence
under the constraints of limited start-up
times, not requiring more than 15 seconds
to execute, and less on some hardwares.
Though start-up time can be traded for
coverage (via configuration changes) to
meet tighter constraints, BIT also features
a ‘fast start’ option. This is very useful in
‘brown-out’ conditions, particularly in flight
applications where the system must come
back up again immediately after a power
glitch. BIT monitors a backplane pin (generally 
connected to an electro-mechanical
power-glitch detector), and if this is in the
‘fast start’ state, BIT will bypass all tests
and jump straight to the operating system
or application.

Once configured tests have completed, BIT
can take a number of actions, such as jump
to the application or go into the BIT option
menu. From this menu, new test configurations
can be made or tests run interactively - for
example, to assist with field diagnosis.

System Test Coverage within a system can
be controlled by a nominated BIT master.
In addition, tests for dumb VME peripheral
cards from the GE Intelligent Platform range
are built into standard BIT code, allowing
these cards to also be recognized and
tested from the BIT master. Results are 
co-ordinated over the whole system.

System-wide memory areas (e.g. local, over
PCI, over VME) can be tested too, including
exercising of block transfer modes. These
strategies deliver comprehensive and co-
ordinated system coverage that can be
tailored to particular configurations.

BIT for the PowerPC family has the capability
to upload tests from a range of GE Intelligent
Platform PMC cards to give ‘plug and play’
test capability. The tests are held in the
BIOS PROM on the PMC cards, and are
uploaded and executed as part of the main
test sequence, after MPE and BIT local
device tests. The uploaded tests can call
upon a range of services from the main BIT
package, e.g. interrupt connection and access
to BIT configuration data. This feature can
assist with field diagnosis, facilitating easy
‘swapping’ of suspect PMCs between PCI
slots or host boards.